Conventional chargers are typically made of two types. One type of chargers has a plug with fixed pins. The pins are mounted on a plug body and protrude from the plug body. Objects close to the pins have a chance to be scratched by the pins because the pins are exposed from the plug body. Another type of chargers has a plug with movable pins. A plug body has a groove. When the charger is not in use, the pins rotate 90 degrees to be received in the groove or sliding along the groove to be hidden in the plug body. For the pins rotated or sliding in the groove, both of them have no block position to stay still without moving when being used, and the pins inserted into the socket are unstable.